Transmissive liquid crystal display has a structure including two polarizing plates with their absorption axes perpendicular to each other (namely arranged in cross Nicol) and a liquid crystal cell interposed between the two polarizing plates. Such liquid crystal displays have a problem in which when viewed from oblique directions, they produce light leakage so that they cannot produce black display, because the apparent angle between the absorption axes of the two polarizing plates is larger than 90° when viewed from oblique direction. Particularly when the screen is obliquely viewed at an azimuth angle of 45° with respect to the absorption axes of the polarizing plates arranged in cross-Nicol, light leakage is significant.
A known method to solve such a problem includes placing an optical compensation layer of a retardation plate or the like between the two orthogonal polarizing plates to change the polarization state, thereby reducing light leakage in oblique directions (see for example Patent Documents 1 and 2). Even when using such an optical compensation layer, however, it has been difficult to completely prevent light leakage in oblique view. There is also another problem in which even though light leakage is reduced using the optical compensation layer, light obliquely incident on the liquid crystal cell can be refracted, reflected, diffracted, or scattered at the interface between various materials such as TFT materials and antiglare layers constituting the liquid crystal display, and part of the light can also be distributed to the normal direction, so that contrast can be reduced not only in oblique directions but also the normal direction.
Another method may also be applied which includes using a diffusing plate or the like in order to distribute leaked light in oblique directions over a wide angle range (see for example Patent Document 3). However, such a method also distributes light to the normal direction where the contrast is originally high, so that the contrast in the normal direction can be reduced. Therefore, such a method has little practical value.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 04-305602
Patent Document 2: JP-A No. 04-371903
Patent Document 3: JP-A No. 2000-187205